The culprit causing this sea star wasting (SSW) even got to starfish in captivity, killing individual animals within days.
Leg of Pisaster ochraceus disintegrating from sea star wasting syndrome.
Now, San Francisco State University marine biologist Citlalli Aquino and colleagues have finally unravelled the mystery, showing something much more complicated was going on. .
By comparing the types of bacteria within healthy sea stars and those suffering from the wasting disease, the researchers found bacteria that thrive in low oxygen environments were abundant in the sick animals, as were copiotrophs - bacteria that like high-nutrient environments.
Experiments back in the lab confirmed that depleting water of oxygen caused tissue-melting lesions in 75 percent of sea stars.
"Sea stars diffuse oxygen over their outer surface through little structures called papulae, or skin gills," explained Cornell University marine microbiologist Ian Hewson.
"This is a very clear example of a trophic cascade, which is an ecological domino effect triggered by changes at the end of a food chain," said Simon Fraser University marine ecologist Isabelle Côté, who investigated the environmental aftermath last year.Â